Water tank testing device



FIG. 1 is a top, front, right perspective view of a water tank testing device showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a bottom, rear, left perspective view.

The broken lines in the drawings illustrate portions of the water tank testing device which form no part of the claimed design. 

CLAIM I claim the ornamental design for a water tank testing device, as shown and described. 